It is known to fold container blanks into a flat folded sleeve for storage and/or transportation Erected flapped boxes can readily be formed from these flat folded sleeves when it is time to place contents in the boxes. Such folding of container blanks and folding machines therefor are disclosed in Lopez U.S. Pat. No. 3,122,069; Watson et al U.S. Pat. No. 4,159,109; and Ward, Jr. U.S. Pat. No. 4,295,581; the disclosures of which are incorporated herein by reference. As part of this folding procedure, e.g. while the blanks are still flat before folding, liquid glue may be applied to a flap portion of each blank to subsequently glue two overlapping flap portions together in the flat folded sleeve state.
The flat folded sleeves are often out of "square". Stacks of the flat folded sleeves can be subjected to an edge beating or "spanking" procedure, while the glue is still wet, to effect "squaring" of the folded container blanks in the stack Also, while the glue (which is usually slow drying) is still wet, there is a tendency for the flat folded sleeves to want to unfold somewhat and start coming apart. This may be countered by pressing down on the above mentioned stacks, or compressing the stacks, until the glue has set.
Although the above squaring and pressing procedures are used with reasonable success, they are somewhat inconvenient and place some restrictions on the particular production line.
It has been suggested that a small quantity of more expensive quick drying adhesive can be used in combination with the cheaper slow drying glue; the quick drying glue "tacking" or "locking" the overlapping flaps together while the slow drying glue has time to dry. See, for example, Neal et al U.S. Pat. No. 20,138 which hot melt adhesive is used to tack overlapping flaps while cheaper water soluble adhesive sets. Over the years, this technique has not been adopted to reduce or overcome the above inconveniences and restrictions found in container blank gluing and folding production lines. This is possibly because in the folding production lines, the folding is completed and the glued surfaces contacted well in advance of the "squaring" operation by spanking.